1. Field of the Invention
The following invention relates to milling grooves in work-pieces, and in particular, milling grooves using abrasive fluidjets.
2. Description of Related Art
Groove milling is employed in fabrication processes for a wide variety of industrial and mechanical equipment. Some examples of equipment for which groove shapes are critical include refiner plates, which are widely used in the pulp and paper industry, and heat sinks in the advanced jet engine industry. In the pulp and paper industry, wood chips are often mechanically processed by passing the chips between rotating refiner plates. The shape of grooves in the refiner plates impacts hydraulic characteristics of the plate that can be critical to the capacity and efficiency of the plate as well as the characteristics of the pulp processed. For heat sinks, the shape of grooves in heat sinks can be critical in heat transfer efficiency.
Abrasive fluidjets can be used for groove milling and offer distinct advantages over conventional machining of grooves. These advantages include reduced fire hazards, reduced power consumption, and high accuracy. At the same time, however, unique challenges are presented in the use of abrasive fluidjets. These include controlling the erosive action of the abrasive fluidjets beyond a certain specified depth; controlling the shape of the groove milled; and properly overlapping the impact of abrasive fluidjets on a surface to produce a groove area larger than the abrasive fluidjet footprint.
Available abrasive fluidjet methods and devices have been inadequate. The shape, contour, and surface quality of the grooves milled are not controlled. The walls of the grooves are tapered with the upper edges being rounded. Also, the bottoms are rough or rounded. These uncontrolled characteristics are undesirable, such as for refiner plates where they reduce capacity and efficiency of the plates as well as produce undesirable characteristics in the pulp processed. There is a need for an improved abrasive fluidjet milling method and apparatus.